1. Field of the Invention
This invention relates to a tunneling effect element that receives a physical-quantity such as acceleration, pressure, load, displacement or the like and produces a strain, and shows a change in resistance that corresponds to that strain, and relates to a physical-quantity to electrical-quantity transducer such as an acceleration transducer, pressure transducer, load transducer, displacement transducer or the like that converts the aforementioned physical-quantity to an electrical-quantity based on the resistance change of the tunneling effect element.
2. Description of the Related Art
In conventional micro-detector elements, there are elements in which the sensor unit for detecting a pressure change in the detected object comprises a tunneling-magnetoresistive-effect element having a magnetostriction section in part of the magnetic member (for example, see Patent Document 1). Hereafter this technology will be called the first prior art.
Also, in conventional stress sensors comprising a tunneling-magnetoresistive-effect element, there are stress sensors in which the tunneling-magnetoresistive-effect element is surrounded by magnetic shielding (for example, see Patent Document 2). Hereafter, this technology will be called the second prior art.
According to the above mentioned first and second prior art, when compared with a strain gage having a small amount of resistance change on the scale of several hundred mΩ, the first and second prior art have an advantage in that (1) the circuit pattern is simple since there is no need for a Wheatstone bridge circuit or the like, and (2) localized displacement in minute locations can be detected since the area contributing to the pressure sensitivity is small.
[Patent Document 1]
Japanese Patent Publication Number 2002-148132 (claim 1, paragraphs [0028] and [0035] to [0036], and FIGS. 4 and 5)
[Patent Document 2]
Japanese Patent Publication Number 2003-37312 (claim 1, paragraphs [0020] to [0028], and FIG. 1)